Hematocrit, which is the fraction of blood volume consisting of red blood cells, is a critical measurement for many blood-based clinical analytical applications. Existing hematocrit measurement techniques are primarily focused on noninvasive in vivo blood analysis or the in vitro analysis of liquid blood. These techniques for hematocrit measurement have incorporated various methods, including optical measurements (transmission or reflectance), centrifugation, and electrical measurements (e.g., conductivity) for the analysis of liquid blood in the body, extracorporeal channels, or cuvettes. They are often slow or hard to automate, and not generally applicable to the expanding field of blood spot analysis.